I know a bit about towing but not the 235.
I would recommend a twin axle trailer of 2000kg. "Invest" may a good term to use as they seem to be hard to get hold of; I am looking one myself!
Beware of sellers on who claim to be on islands like Jersey or the Scottish isles and who seem determined to get you to pay for delivery up front.
I see also on the fleet page that a single axle trailer was available for £1,600 in 2002. I would go for a twin axle for greater stability whether towing or not.
£1,200 to £2,000 seems to be the going rate but new ones from SBS are about £3,000. SBS would also advise you well if you went for a new one.
http://www.ntta.co.uk/