There isn't really a way of acclimatising shade loving plants to sun. The onmly way is to create a shady part of the garden with taller sun loving shrubs/trees. This will take time but will work. Keep them in pots somewhere shaded if you can or else they will soon suffer in the sun. Wouldnt of thought snowdrops would mind to much as generally out before the heat of the spring/
summer comes

The bamboos would help provide some shelter. Would shade netting help in the meantime Nicky, while the sun loving shade providers get going?

Shade netting would help, but would need to be permanent as they can only cope with semi shade or shade.

Camellia's not an issue, it doesn't mind full sun - what it doesn't like (or rather, what you won't like) is an east facing position where early morning sun hits it in winter - frost on the buds, sun hits them, buds drop, no flowers. Otherwise, plant it where you like, it'll be fine. Hellebores will tolerate some sun, but being smaller plants, they can be planted underneath shade giving larger plants. The bulbs will be fine wherever you put them. The Acer may be a problem - it needs dappled shade, so that will need to be positioned carefully to avoid its being out in the midday sun, so to speak. if the garden is full on south facing, the right hand side should be out of sun by lunchtime, so may be less trouble for your Acer.

Thanks all - the acer and camellia are currently shaded by a beautiful contorted hazel that shields them from the early morning east sun, but lets them enjoy the light later in the day. The new garden will be full on South, currently with no shadey areas, but a garage runs along the width of the bottom of the garden and I could construct a shade canopy attached to that, or use the summer gazebo, temporarily? The bamboos are over 8 feet tall, so that will be fun moving them. The garden is very much a blank canvas, no borders and just grass, so we are looking forward to creating some 'rooms' to shield our shade plants (that we have come to love) and looking forward to re-acquainting ourselves with the sun-loving plants, that we haven't seen for 7 years!! Will be moved before Easter, so at least it won't be too hot to start with. Any suggestions with the shrubs and trees to provide the shade?

Buddleia davidii for a start - that'll be at least 8 feet by the end of its first summer if you buy the right variety. Provides lovely dappled shade beneath. Another rapid grower is Sambucus (Elder) - S. 'nigra' is very popular, and there's a yellow form S. plumosa aurea. Cornus alba 'elegantissima' is reasonably fast - all three of these are deciduous and can take (and in the case of Buddleia, needs) hard pruning. Otherwise, you have a wide choice of almost everything else in terms of shrubs.

Oh, bamboo thanks. I have a self-seeded buddleia about 2 feet high in a pot and an S Nigra black lace, that I took as a cutting about 2 years ago, and they are both doing quite well. I suppose we have just got used to the plants in our garden being 'shade' plants, when there is some sun down one side (but not in the Winter and not for long in the Summer). My head is plotting and scheming with plans for the OH to construct a pergola backing on to the garage to grow something over and provide a shady area for some of them and there is a little path down the side of the garage that will probably be ok for the Lily of the valley and some of the ferns. Have got other shrubs - a lovely white Hydrangea Paniculata, a Magnolia Susan and a Salix 'Hakuro Nishiki' just waiting for the right spots to go in. I kept them in pots to make the most of the Spring and Autumn sunshine that I do get and then settle them down for the Summer - sounds daft, I know but they haven't objected so far (apart from being smaller than if they were in the ground).