We went to Legoland this year and stayed in a Premier Inn 20 minutes away. It cost £130 for 3 of us to have 2 days in Legoland and one night at the hotel. It also included my ds's evening meal and breakfast for all 3 of us.
It was a bargain. Staying at the Legoland hotel would have cost £420 and not have included any evening meals.
Our ds's would love to stay in the hotel. We could go next February half tern when Legoland itself is closed and stay in the hotel for 1 night (check in at 3pm, check out by 10am) with breakfast included for £142.
There's plenty to do in the area, and we'd have time to use the pool at the hotel which I don't think we would if the park was open but I wanted to hear what the hotel's like in off season.