Betfair 50% Cash out up to £250

max stake is £25, so if anyone cashes out for £250 profit they’ve done very well.
I’d say put it on a football team and settle for a smaller freebet which is more likely (and reduces liability).
Otherwise £25@10/1.

The offer is available on multiples as well. I think the most profitable way would be to put in a few odds-on favs going off at different times and sequentially lay them. If your first few selections come in then you will have a bigger cashout available. If you’re putting it on one team with high odds then you’re probably not going to get the option to cash out for a profit barring a miracle.