There would be no problem if he had been widowed between wives.
Answer
You should talk to your church and find out.
In the Catholic faith the only way that you can be married more than once is if your spouse dies, as noted above. Because every marriage is "until death do you part." One small problem, no one may TAKE Holy Communion, you may only RECEIVE Holy Communion.
The Catholic Church is the 'communion of holy people.'
You need to be baptized Catholic, and have made your first Holy Communion, you need to be in a state of grace, otherwise, you need to go to confession before receiving Holy Communion. You must be fasting for one hour prior to receiving Holy Communion. If divorced, you need to get an annulment before attempting marriage again. If married, you need to be married before a Catholic priest, or dispensed from such by your Bishop.
Roman Catholic AnswerThe only people who may receive Holy Communion in a Catholic Church are Catholics in good standing, who have been to confession at least once in the last year and have no mortal sin on their souls; they must have made their first Holy Communion and be fasting for one hour. A protestant, regardless of their marital status would never be eligible to receive Holy Communion until they had converted.
Nobody can take Holy Communion in a Catholic Church, you may only receive Holy Communion from the priest, and then only if you have been baptized in the Catholic Church and previously made your first Confession and First Holy Communion. Bottom line? An Anglican may not take communion in a Catholic Church.
In the Catholic Church, the next is traditionally Confirmation.
Roman Catholic AnswerWhether or not you can receive Holy Communion depends on a number of things, you would need to make an appointment with a priest to talk this over. The person to whom you are married will also have to talk to a priest and arrange to have their marriage submitted to the tribunal to see if it can be annulled. In the meantime, you both need to be living as brother and sister, and go to Confession, then you may receive Holy Communion.
.Catholic AnswerOf course not, an Anglican is a protestant, a Catholic Church is Catholic. An Anglican may receive Holy Communion in a Catholic Church after completing RCIA classes and being brought into the Church at the Easter Vigil, but if they wish to remain an Anglican, they are, by that very fact, proclaiming that they are not in communion with the Catholic Church, so to receive Holy Communion in a Catholic Church would be a lie and dangerous to their spiritual well-being. Aside from all that, Catholics to not "take" Holy Communion, they "receive" Holy Communion.
Quite simply, the bread and wine received at a Pentecostal church would not be Holy Communion.
I am assuming you mean how different is communion in a non-catholic church vs. Holy Communion in a Catholic Church? In that instance, Holy Communion in a Catholic Church is, literally, the Body and Blood of Our Blessed Savior; brought about through the direct intervention of the Holy Spirit working through the priest who pronounces the words of consecration. For a Catholic to receive Holy Communion in a state of grace confers more grace through fulfilling Our Blessed Lord's command to eat His Body and drink His Blood. For a non-Catholic or a Catholic in a state of mortal sin to receive Holy Communion is to eat condemnation as St. Paul points out "and this is why many of your are ill and dying"
You may never "take" Holy Communion in a Catholic Church. You MAYonlyreceive Holy Communion after you have been baptized, and in the Latin Rite, made your First Confession.
Roman Catholic AnswerFirst, let me extend my condolences on the death of your Nana, I am so sorry. If you are a baptised Catholic, who has made his first Holy Communion, and have gone to confession, then, of course, you may receive Holy Communion. If you are not a baptised Catholic or have not made your first Holy Communion, then you make what we call a "spiritual Communion" which is what a Catholic would do if they have not been to Confession, asking Jesus to come into your heart.
For a Catholic to be in good standing, and to be able to receive Holy Communion, then they must not be in an irregular situation such as you describe, an objective state of sin. For the Catholic to be in a state of grace, and thus to be able to receive Holy Communion, he or she would have to fix the irregularity in his life either by obtaining an annulment and validly married the individual or by separating from them. It might be possible to receive Holy Communion and get back in a state of grace by just practicing continence, until such time as they could be validly married, but this would be an individual decision of the person's confessor. For a more thorough answer for a similar scenario, read this, written by Father Shane Johnson, a New York priest: (see link below)