Thanks for your suggestion, Obelixx. I would like to visit the Edinburgh Botanical gardens in April, May or June as I feel gardens look their best at that time of year. Unfortunately, it is also the time when I am at my busiest in the garden, so have to limit holidays to 8 days maximum during those months.
Instead of Edinburgh, we are now thinking of going back to Swaledale in early June. The countryside, with its fields of buttercups, beautiful River Swale and wealth of bird life, is one of my favourite places in the UK. We could visit Eggleston Hall Gardens for a day trip whilst in the area. We have been there before in 2011 and enjoyed the gardens very much. The lupins were magnificent.
We visited Harlow Carr a few years ago when we were members of the RHS. It is lovely there, though I prefer the RHS gardens at Wisley and Rosemoor.