We're on quite a tight budget and are struggling to find a honeymoon that will be both a really lovely, special time away together and that will also fit into our budget of £250 - £300 each, tops.
We were looking at somewhere in the UK purely to cut travel expenses, but I'm concerned about the weather in late September as I don't really want to spend our honeymoon shivering and soaking wet . . . not quite the sort of thing we want!
One option for a holiday destination which is not reliant on good weather is Centreparcs. There are 4 locations in the UK; Longleat, Elveden Forest, Sherwood Forest, and Whinfell Forest. The Parc is under a dome, so you can enjoy a range of activities in the woodland setting without shivering or getting wet. Most locations have an on-site spa and extensive leisure facilities.
If that doesn't appeal, then I can recommend renting a cottage for a week and taking long walks in the country, or snuggling up beside the fire with a glass of wine. If you are concerned about the weather in September then I'd suggest looking in Cornwall or Devon, which has a more temperate climate.
If you would prefer to travel further afield, why not go to Marrakech in Morocco? If you stay in a Ryad (a converted town house built around a fountain courtyard) you can get quite cheap deals. Prices in Morocco are low, restaurant dining is relatively cheap, and you can pick up some beautiful souvenirs in the souks. Marakech is within a taxi ride of the Ourika Valley which makes a great day trip for a hike or swim in the waterfalls.