The Side saddle association do taster days but as you are near Talland I would go there it is great fun. I did it at my local riding stables a few years ago.
(I even have a habit I refuse to bin it incase I ride side saddle again)
I did side saddle a few years back and found it ok. I even did a bit of showing but it wasn't for me. I found it relatively straightforward the most difficult thing was to sit straight and not turned to the side your legs were. It is certainly a very secure way of riding and not easy to come off.
I made the mistake of telling kiri that if T ever hit 16.2hh then we'd take her over to Janets to see if she'd take to SS - at 3 1/2 and a good 16.1 I think Kiri may hold me to it!
I'd say the most important thing is relaxed, flexible hips and good core muscles - then you just need to sit tall and square and its pretty much the same as astride but with one leg! Oh and train the right foot to point down and in (which is infact outfrom your body) is fairly odd and takes a bit of getting use to!
Jill Carenza at Stanton near Broadway in the Cotswolds. I had a couple of taster ss lessons with her a few years back - fantastic and she got us jumping in our first session.....scary but superb!!! She has an amazing pic of herself flying a vast hedge ss while out hunting - has to be seen.
SS not listed on her website but I'm sure she still offers it.