With those uniques you could easily earn £30 from ppc, so that makes a yearly rental of £360 straight off.
You hear of a lot of people saying, ooh I rent my domains out, err no they dont, trust me, the percentage is very very low.
If you have someone truly prepared to rent your domain, you should take whatever they offer, explain to them that you can earn more, but you will accept £250 a year, increasing in years 2 and 3 then stable for the rest of the 5 year contract.
They will of course need an out, and that should be 6 months worth of payments.
In year 5, if they are still trading from your domain, you can charge whatever you wish.
People only rent names for short term projects, long term like this would be, is quite simply not economical to any business. They have no control over the domain, so why on earth would they build it up, with the potential of it being pulled away.
The maximum I personally think you would get is £500-£750 a year, and even then I'm being rather generous for a change. You see the potential, and I see the potential, but you will find the rental figures scare people off.
You should meet with the proposed tenants and look at their business plan, sign a non disclosure if they are worried you will pinch their ideas for the domain. After you have done this, choose one of thier revenue streams that you like the look of, and ask for a percentage share with a small monthly rental.
This way, you get some rental, a percentage of the revenue stream you choose, and it also gives your tenants peace of mind, knowing that you have a vested interest in the success of the site, the more they earn, the more you earn, less likely to pull the domain in 5 years.
Some unscrupulous people, may think it would be a great idea to rent out a domain for a couple of years and then cash in on the traffic etc, be careful if that is the case with anyone reading this, as you will find that the tenants will probably be able to claim similar protection to those of sitting tenants in regular life.
This could come into play when you decide to sell also, they could simply refuse, unless you sell the domain with them as sitting tenants.
Best of luck, its a great name, I like Wakefield