There are many ranges of mountians in Great Britain, including:

in Scotland -

Cairngorms

Cheviot Hills (also in England)

Grampians

Northwest Highlands

Ochil Hills

Scottish Highlands

Sidlaws

Southern Uplands

Torridon Hills

in Wales -

Berwyn range

Black Mountain (range)

Black Mountains

Brecon Beacons

Cader Idris

Cambrian Mountains

Carneddau

Clwydian Hills

Glyderau

Moelwynion

Nantlle Ridge

Preseli Hills

Pumlumon

Rhinogydd

Snowdon horseshoe

Snowdonia

in England -

Berkshire Downs

Bodmin Moor

Cheviot Hills (also in Scotland)

Chilterns

Cotswolds

Dartmoor

Exmoor

Lake District

Lincolnshire Wolds

Malvern Hills

Mendip Hills

North Downs

North York Moors

Peak District

Pennines

Quantock Hills

Shropshire Hills

South Downs

Yorkshire Wolds