Decent bike shop in Wimbledon area?

After several months of lurking, here I am registered, prompted by your post, so thank you for asking.

There are several good-ish ones nearby. Not too sure about the one nearest you near the railway station, but it's worth visting:
Smith Bros on Chrurch Road in Wimbledon Village. Sells his own brand of re-badged MTBs and quite a few second hand bikes. Worth checking out for '80s racers in need of conversion.

It's where I got my first bicycles (second hand emmelle or summat), they're decent bloke and are worth checking out, it's a very small shop and don't expect a good selection of bicycle parts.

Action Bikes on Wimbledon Broadway is OK-ish in an Action Bikes kind of way.

That's 10 second ride from my home, they're ok, the staff are those who not exactly knowledgeable in cycling, but the mechanic is a top bloke who know his stuff.

Star of the show is AW Cycles on Merton High St. Propoer oily finger nails and overalls set up. They sell laughably crap bikes, but very good spares. On a good day he'll let you have a rummage through his spares box.

1+. crap bikes (just to keep the business going), but top bloke.