Hi Aerofoil1,
Been there, done it. I can't disagree with any of the posts here but they are being very kind.
£13000 is not a lot for a four seater but not impossible. There are people out there desparate to move on aircraft so there are bargains to be had.
Running costs are another thing altogether. An EASA/CofA or whatever you would probably need to get four seats will cost £5000 a year maintenence in a lucky year. That's what it cost our group this year for a five year old aircraft. Imagine what it costs for a 30 year old one. Plus insurance plus parking plus CAA fees.
10 years ago I owned a 25 year old Archer. I loved it. I had no parking charges but it cost me £10000 per year not including fuel or engine fund.
You also said day VFR only. It's amazing how quickly you may grow out of that point of view.
I am now a member of a group with a modern aircraft. It's like having your own at a fraction of the price (and worry). Availability has never been a problem and the tasks are shared.
Now for the arithmetic £6000 maint + £2000 ins + £1500 parking + fuel for 30hrs @ 8gph = £2300 total £11800 = £393 per hour for an old aeroplane!
Alternative is leave the family at home.
D.O.