We went away for a weekend with our toddler last year to Ickworth House in Suffolk. (
http://ickworthhotel.co.uk) It had everything we needed, good food, very children friendly and a heated indoor pool that was available all day (some hotels have restricted hours for children). The biking was excellent, it was the first real outdoor fun we had altogether since having the LO. They had a baby listening service at night but I wish we had brought our own baby monitor with us to cover the daytime nap as well. Cant remember exactly but Im sure its about 1 and 1/2 hours from London.