Most accommodation providers are offering free cancellation. Only book your travel and accommodation if you can cancel it nearer the date.
The vague message from the government yesterday was that nothing is going to be open for Easter. I would be quite surprised if you will be allowed to travel from England in May. Probably still not able to travel outside our local authority area in Scotland.
September would be a better option but if you have free cancellation there is nothing lost by booking for May.
All the best