£500? The gov't would spent that much. You can do it for much less. £300 max, incl assessment payment. For example: train to Southampton - £65 with railcard, or £100-ish without; 2 overnights - £45 (1 night @ CTC, £30, and 1 night someplace cheaper on your return route, £15).
From Southampton train station, walk or take the free shuttle bus to the Hythe ferry pier, hop on the ferry (<£5), and get a taxi up to Dibden manor (<£5). Into the bargain you get to ride on some sort of wooden train along the pier at the Hythe end to save a 10 min walk, which I thought was pretty cool.