Hi Steve
Great that you're looking to get out and about again.
You live in an area with loads of quality fishing available.
The Whiteadder is a cracking stream and can be really good, however access can also be a bit wild. Great if you (like me) love that style of fishing, not so good if mobility is an issue. There's a club on the lower section and i'm sure the members will point you in the right direction.
The Reservoir is also good with smaller, hard fighting and free rising fish all over it, a great place to wander its shores chasing those residents.
You've a few rainbow waters close to hand the best of which is the excellent Coldingham Loch which is now members only in terms of fishing access (unless you stay in a cottage), but it's a beautiful place and well worth visiting / enquiring about a cast or two there, maybe even joining the club?
However, all that said, you've the Mighty Tweed and loads of access availability on an excellent trout and graying river. Quite a few clubs along its length which offer fishing both directly on the Tweed and it's tributaries, as well as a few offering club lochs as well.
Love the Borders for fishing, truly spoiled for choice, and if this isn't enough then you've the reservoirs around Edinburgh which can be excellent.
Tight Lines.