I want to say "no" you can't do this based on what you've told me.
What matters here is the size of the wire, 240V is 240V and that part of it doesn't matter. A dryer uses #10 wire for 30 amps and a washer uses either #14, or #12 for Canada vs US. If you were to just switch out the receptacle you would run the risk of burning up the 15 amp wire as it's not designed to carry that kind of load continuously.
If you have a wire stripper that has the awg wire gauges on it and it measures out to #10, then you can swap out the receptacle and breaker and convert this to suit yourself.
If in doubt, always consult a licensed electrician.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
If you do this work yourself, always turn off the powerat the breaker box/fuse panel BEFORE you attempt to do any work AND always use a meter or voltage indicator to insure the circuit is, in fact, de-energized.
You DON'T! The washer needs to be on a separate dedicated circuit; 120v, 20 amps. The dryer needs to be on a 240 V, 30 amp dedicated circuit. Trying to do otherwise is unsafe.
The UK uses 240V, so your dryer will probably work, as the US uses 240v in homes for dryers. However, your washer won't as the US uses 120V for washers.
You cannot use 2-120v outlets to power a 240v dryer. You can convert a 240v dryer outlet to power 2-120v outlets if they are supplied with a neutral. This requires a competent electrician. Do not do this yourself.
if i have a breaker that has a 120/240v and my dryer has a 240v plug can i change the receptacle to a 240v
I assume its 120V already: so, yes, you'll have to wire for a 240V receptacle (240V uses 1 more current carrying wire than 120V). Even if there were enough wires at 120V you'd still need a larger size wire for the combo unit. An electric dryer is a beast with electrical current.
Disregard the neutral
Probably not. The average dryer will pull 25amps.
Probably, because a "220V dryer" and a "240V dryer" might be the same thing if you're in the United States. Most electricity in the U.S. can vary within about 5% of 120V (114V to 126V) for single-phase, two-wire current (commonly called "110"). For single-phase, three-wire current (split-phase current, commonly called "220"), the voltage can vary within about 5% of 240V (228V to 252V). So, as long as the holes in the outlet and the plug from the dryer have the same configuration, the dryer should work. If not, replacing the outlet so that it matches the plug should be all that's needed.
An existing outlet can be converted by replacing the 30A circuit breakers or fuses in the circuit breaker or fuse box with 15A breakers or fuses. The 30A outlet should also be replaced by a 15A outlet. This is all that is required if the wire from the supply to the outlet is 10, 12, or 14 guage. The existing wire should be 10 guage wire to handle the 30A and there will be no problem in the same wire providing the 15A.
No. Call an electrician. 50 dollars is cheap compared to having your dwelling burn up.