SQUASH FITNESS TRAINING

So I've decided to pick up the racquet I bought nearly a decade ago and get into the game. I had a mini assessment where the pro said I lacked, among other things, flexibily and core strength.

Okay. I am not fit enough for squash (or much of anything else) but I can go ahead and start training.

Are there any sport specific exercises I can do? I'm hoping to play in the beginner league in five weeks but I really should be in better shape for this sport.

Any tips, suggestions, links--all welcomes graciously.

Thanks all.

p.s. You folks in the UK KNOW squash-- where can I go for some good drills ,etc, to develop my shots and placement? My backhand is non-esixtant as this time.