I am in the South West, so a bit too far away to offer direct help. Maybe someone else on here will volunteer.
As a starting point, the bullion value of your sovereigns is around £727 each at the moment. If they are in particularly good condition or a rare date, they may make more. If you sell them, most dealers would want to pay less than that as they can only sell them to collectors at bullion most of the time, and they need to leave a margin. (Many Jewellers are particularly tight, usually offering only half bullion value!)
Maybe the "Yorkshire Auction House" featured on the TV might help? They have a resident coin expert.
On the gradings you have got, bear in mind that "Good" in coin terms is almost derogatory. Collectors for modern coins will mostly only start at Very Fine or better.
P