You could be lucky, but IMO £4-5k BMW is a terrible idea. As likely to be a money pit as not.
The Legacy estate sounds a good suggestion to me. but might take some finding.
Whatever you buy at that price, choose carefully and don’t get sucked in by luxury extras.
TBH I can enjoy driving most things. These days the most boring cars to me are those with too much power. You use a Fabia as the example of a boring car, but I even like driving my wife’s Roomster (although it does have the 1.2 TSI so is decently nippy). It’s more fun than my automatic diesel Outlander.
The only really tedious cars I have driven in the last 20 years are a Cit C1 (too drony) and a Hyundai i20 I had on hire for a few weeks that was so unmemorable I can’t even remember what I didn’t like about it! I think it was just that everything felt insubstantial.
Bearing in mind insurance costs and your age, it might be worth looking at insurance groups now.
There will be 10 times as many Focus estates to look at as Legacies, and they aren’t bad to drive.
Don’t ignore the tyres, they cost money and four decent premium tyres say something about the last owner. Always check the MoT history.
EDIT: Should have said my brother has run a couple of relatively cheap V70 turbo diesel estates to big mileages . They were less rouble than he expected them to be. But he is a mechanic by trade, abeit now retired.