As SmithOp has stated, timeshares in the UK are a rare breed and those that do exist are, in my experience, often tired, dated and do not attract particularly good reviews.
What we've found is the cottage rental industry is a far better option. There are litereally thousands of private cottages and houses being rented out up and down the UK and whilst they don't offer the resort feel of a timeshare, very often the accommodation and facilities are better than what is offered in much of the UK timeshare resorts.
We've stayed in a fantastic thatched cottage on the Dorset coast, minutes from a fossil laden beach and a plethora of cosy pubs and a very old and interesting church within a few minutes walking distance plus the benefit of separate bedrooms for the kids, a substanitally equipped kitchen and a fully stocked open fire to curl up to. We've also spent a long weekend in a beautiful, historic four bedroomed house in York, 5 minutes walk from the Minster and just a few minutes more walk from York train station (train from London to York is 2 hours) and pretty much everything worth seeing in York is doable on foot. We've stayed in a barn conversion in Cornwall, a house in the Wye Valley and so on, all great, interesting places, some with a lot of history and character that you won't find in a timeshare.
Now, if you're only option is trading then a private rental is going to be an additional cost but it's worth bearing in mind if you're struggling with securing a trade.
