The Reformation, eh? Well, here's a few things that might interest you. I've picked out specific bits relating to the Reformation, but they've been picked as they're nice places in themselves:

Chester is a lovely city in it's own right (loads of history going from the Romans forward to the industrial revolution, via the English/British civil war(s)), but Chester Cathedral is probably the best preserved monastic cloisters in the country. Most of them were destroyed, you see, but the monastry in Chester was handed over to the Church of England to be turned in to a monastry.

From there, there's a couple of interesting day trips. Valle Crucis Abbey in Llangollen was a monastry which didn't fare so well (although still cuts an impressive sight). Llangollen itself is beautiful, lots of interesting things around the area including a world heritage site at Pontcysllste Aquaduct just down the road.

Liverpool is also well worth a day trip from there, possibly even a couple of days.

If you want to go earlier, there's a lot of (English-built) castles along the North Wales coast. I'd suggest Conwy as being a good balance of easy-to-get-to whilst being mightily impressive. The town is also really nice and you can easily spend an afternoon wandering around it's streets, which feel very medieval!

You're probably also going to want to go somewhere like Oxford or Cambridge, which were major players in catholic and protestant thought respectively. They're also lovely cities to visit. I prefer Oxford myself.

London is an obvious choice, with more than it's fair share of history & historical interest.

Finally, Edinburgh will be a good base for the Reformation in Scotland. Lots of interesting churches, museums, chapels etc.

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The latter 3 suggestions come up all the time on here on people's itineraries, so I'll not go in to much detail as I think they've been covered well. Chester usually & understandably doesn't come up *as* much, as normally the suggestion is to go to York instead. That makes sense, it's between Edinburgh and London, and if you're looking for that specific style of city there's a good argument to say it's the better of the two. However, specifically for people interested in slightly deeper history, I feel there's WAY more either in Chester or easily accessible from Chester. So you're losing a bit on the city itself, but gaining far more via the surrounding area (not that Yorkshire isn't incredibly nice!!)