Hi,I think it's probably safe to move them in winter. That's when they dormant, and is also when you can buy bare rootstock. If you really have to move them before then, pick a week when the temperatures are going to be very low (below 25C), for the whole week. Dig a trench around each plant - make sure it's a reasonable distance away from the main stem so that you minimise the damage to roots. You will probably need to cut the roots when you dig this trench, but as long as you maintain a reasonable number of feeder roots the plant should survive. Before you start digging the trench, give the plants a good drink of water, with some seaweed solution mixed in (like a weak tea). This helps to reduce the transplantation shock. Once you have dug them out, put their roots into a bucket of weak seaweed solution until they are ready to back into the ground. if that's likely to be days rather than hours, it would be safer to repot them until they are ready to back into the ground.Since these plants are in your garden, why not just take some cuttings and propagate those to put into your allotment? That way you keep the original bushes and can always replace the ones in the allotment