Iam in leicestershire,and interested ..would travel if you find any where

There is the Doncaster Dome nudist events (if they are still held) and I'm sure there are other nudist swims in the area - just Google it, or check the links here or on the BN site.

If you want wild swimming (i.e. not in a public pool) I suggest using Google maps and look for some farmer reservoirs (I have one not 100m from me and another 800m away), and in the summer I normally swim nude once a day (granted I walk there nude as well), much bigger than a pool, and naturally more dangerous (no life guard) - but if your sensible and a good swimmer I recommend it. 

Another alternative if there is small local pool near you and you know other nudists in the area, is to ask the pool owners if they do private hire and if its OK to hire it out for a nudist swim (you can blame it on the GBSD); many nudists swims are in public pools hired out for the occasion. As I've said on other threads if you don't ask you don't get - all they can do is say no, but don't be surprised if it a yes; you can then advertise to make others in the area aware of the event. Several people here organise such things and I'm sure they will give advice if you go down that route.

Thanks for the advice!
I'm asking more in terms of an outdoor location so I'd better get on google maps.

I'd suggest looking on wildswim.com. There are places to swim, you might just have to pick quiet times in the week to try doing it nude.

As for swimming in any kind of reservoir, I don't think that's particularly good advice.

Came across a pool on the path below Snake Pass today that we'll have had back for when it's a little warmer. It's on the River Ashop. We accessed it from a path off the A57 a couple of hundred yards north of the Snake Inn, the Forestry Commission sign calls it Snake Woodland, although on the OS map it's part of Lady Clough Moor. Follow the path down from the road (the one between the crash barriers - https://goo.gl/maps/BrEUB2L2GtfLEVQf7) to the stream and follow on north up the valley for about a quarter of a mile and there is an obvious pool in the open.
Didn't actually swim, but with the remains of a fire there it's obvious others probably have done recently. Not huge but certainly looks deep enough to properly float in, and the water is the typical peaty coca-cola stuff you get fresh off the moors.

The path was quiet enough in the mid-week that I enjoyed a fairly decent naked walk, and wouldn't have felt inhibited to go for a skinny dip at the risk of a handful of people seeing from a distance (as it's slightly off the path).
Weekends and summer holidays might be a different matter.