I looked into various options a while ago for a group of us (10/12) but it never materialised to getting something booked for one reason or another. What I had proposed is still available and pretty wallet friendly compared to flying/staying in Madrid that weekend. If anyone is interested, I'll stick brief details below (just checked some of them now for prices)…
Friday 31st May, Manchester to Valencia, 16.10 - 19.40
Monday 3rd June, Valencia to Manchester, 14.35 - 16.15.....£160pp return (Ryanair so luggage is extra)
Hotels in Valencia are still looking good for pricing and availability. Can get a room for about £50 a night if you're happy to stay further out the centre, or get a solid 3/4* central option from around £85+ a night (Trivago is your friend for that)
If there is a group of you, probably say 4+ people, then looking to rent an apartment would be the more cost effective option. I haven't checked just now but when we were looking at 5 or 6 bed apartments there were a number available right in the centre and it really brought the average total down per person, try Airb&b but also homeaway website.
Valencia - Madrid train takes around 1 hour 45 minutes depending on which service you choose. I think they have dynamic pricing similar to that of the UK where the prices increase the closer you get to departure. Just looked now and there is a direct train leaving Valencia at 10.40, into Madrid at 12.27 on the Saturday lunchtime for £19.97. Coming back Sunday morning, the first train isn't until 08.40, back into Valencia for 10.33, again £19.97. (as per Trainline website) That does make it a very long night, even longer if we get there and lose! If you're in a group or encounter some people who have done similar, jumping in a minibus or large cab and breaking the fare many ways might make more sense than hanging around until 08.40. There is also a flight from Madrid to Valencia that morning, leaving at 08.10 (£37) so you could book that and head to the airport in the early hours.
Just done a very quick search and one way minibuses from Madrid to Valencia start from £741 for a 10/13 seater, through to £787 for a 16 seater and 'only' £798 for a 19 seater which actually works out pretty good value if you could fill it for the 360km journey.
So as an example, if you're a couple, want to stay in a decent central hotel in Valencia, happy to pre book the trains to/from Madrid then you're looking at about £340pp for the weekend including those Ryanair flights (another option would be to book the flights which will be none refundable, and book a hotel that offers free cancellation, so if City don't make it you can choose to cancel and write off £160 or crack on and have a weekend in the Spanish sunshine)
Hope someone finds that wall of text either useful or at least interesting!