I'm 22 years old, will I be able to rent a car in Great Britain?
Do you have a driving license for at least 1 year?
OK, then look here:-
At STEP2, click on the link "IMPORTANT INFORMATION' displayed to the right of the car photo of your choice. This will open another smaller window and if you click on "DRIVER" you will see what age restrictions there may be and any associated fees. Try a few different car models / suppliers, as they do differ.
I have a look as well..This is for example what Europcar says at the location you searched for:-
If you are between 22 and 26 years old you must pay at the desk a young driver surcharge of GBP 32.50 per day. This fee is not included in the quoted price and payable on arrival.
You must be 22 years of age to rent Mini, Economy and Compact car groups.