When I was ordering the shed I was advised to paint it to protect it from rot. The recommended product was Protek Royal Exterior Wood Finish I was kind of sceptical as this was £60 for a 5 litre tin but I managed to find it at that link for £45 delivered, even so how much would 5l cover?
Well it seems quite a lot. So far I've painted the shed twice [with the left end wall 3 times] and I've still got about 25% of the tin left. So I've no doubt 5 litre tin would paint this 10' x 6' shed three times over.
Now the opacity isn't compltely solid, the colour gets stronger each successive coat and you can still see the wood through this end after three coats. I'll probably be doing four coats on this end and side leaving the back and right side on two. They're not as visible and less exposed to I expect them to receive less weathering as the back is covered by a hedge and the right is sheltered by the second shed.
However, I'll monitor the situation over the next year or so and should I feel the need I may paint it with an exterior house paint just to bulk it out, it's much cheaper and again it doesn't have to match perfectly, particularly the back, but for now this will do.
Incidentally the colour of choice was Cornish Cream, whicc is another [tenuous] link to my past in the four years I spent at university in Cornwall. The other shed in the garden is black/dark oak but I thought this would be too imposing to be dark, whereas this is quite bright I think it does evoke a beach hut feeling, so I'm quite chuffed.
I'm just waiting on the electrician now and opportunity in the weather to finsih off my tin of paint.