A share really only makes sense if you are going to do a reasonable number of hours, i.e. perhaps 30+ per year. Obviously schemes vary hugely, but most will involve a monthly amount, maybe £100 or more plus a wet rate of anything from £60 to £90 ph. My local club will rent a Warrier for £120 wet, no ties, entirely PAYG.
I wouldn't constrain yourself to the airfield you've been training at unless it really is absolutely the only one you can get to. There are plenty of smaller strips around with shared planes based on them and they are usually better value - you need to seek them out. A few hours/approaches with an instructor and you'll be fine.