Good advice about getting family etc support for one's flying
Re prices, yes you can buy a working 4-seater plane for £20k but it will still be a relative wreck.
Somebody who knows what they are looking for (in engineering terms) can get great buys but a novice is just likely to get shafted. I've seen some awful stuff for sale (a friend was looking recently). If one is new to this game, it's best to not buy at the bottom of the quality scale. £30k will get something a lot better. But you need spare money after that for "suprises"; say another £10k.
For serious IFR, we are talking upwards of a Piper Seneca.
There are very capable IFR singles, but all way out of this man's price range.
The last thing I would recommend someone new to this to buy would be a twin. Loads of money p*****g out on operating costs.