The owner of Rush Green charges a fiver a landing. You would have to book a taxi to pick you up as there are no facilities nearby apart from a scrapyard!
I'm surprised at the 800' request, the usual minimum is 1,000' on the Luton QNH which gives us 500' agl over the hill which is below the downwind leg of the circuit. If I'm entering the zone from the North I usually ask for 1,500' descending to 1,000' when entering the circuit.