I have been asked to manage some hives for a local wedding venue. They would like to sell the honey etc. How much is the going rate for doing this in the UK?
Well ... you've had all the negatives in the beeworld thrown at you so far ! Looking at the positives - it's a nice site and you've found a spot well away from any commercial activity, you have a few years of beekeeping experience so, hopefully, you have some idea of what you are doing, regardless of any BBKA qualifications (which are treated with scorn by some on here).
There appears (from what you say) to be no hives currently on site.
I think what I would do is give them a cost for a couple of colonies with hives, supers, queen excluders etc.and bees as a starting point (capital investment). Then, separately, give them a breakdown (but not a cost) of what you are prepared to do to manage these colonies viz: weekly visits/max 10 day visits from May to September include travel time and distance (it soon mounts up). Insist that there will have to be a secure storage container of some sort on site. Winter visits and a set number of adhoc 'unscheduled' attendances.
Include Varroa treatments and feeding.
Explain that the honey will require extraction and jarring up - include the time that it will take to do all this and explain that a crop cannot always be guaranteed and find out if they intend selling the honey in 1.5oz jars or 8oz/12oz and give them a likely cost for the jars, lids and bespoke labels.
By the time you've costed the capital equipment and consumables your time and remuneration is going to be what the market will bear. If they have not collapsed in shock at the start up and consumable costs of a small beekeeping enterprise then they won't collapse in horror at the cost of your involvement.
You then need to work out what your personal cost of involvement is ... add up all the hours and decide how much an hour you are worth. Include all the travel times, the extraction and jarring up time as well as the time you anctipate for inspections ... then add on a margin for buggeration, add in your travel costs and when you have picked yourself up off the floor, double it. Excel spreadsheets if you are up to it are your best friend....
What drops out of the bottom is your starting point - you can always negotiate but it's a lot easier to reduce your fees, in order to get or keep a deal, than it is to increase them. If the kit, livestock and the honey is all going to belong to them you have no security and all your income will come from fees.
You will need to agree what their plans are for expansion and how you will deal with the possibiity of bees swarming and whether the stock increase is theirs and if it is ... the cost of each additional hive and the additional costs you will face in managing the additional colonies. Give them a flat annual cost for your involvement - payment in four separate installments on the quarter days - or monthly if you prefer.
If you get it right at the outset it can be a useful income - get it wrong and either you will be out of pocket or your client will feel cheated. You are not going to get rich on it but there is an income available as long as your client understands that everything has a cost and the honey harvest may only go part way to covering the costs until they reach a certain size and the capital cost has been absorbed/amortised.
Good luck ... additional income is always welcome but treat it as a real business and do your sums properly - without guessing or finger in the air 'estimations'.