Thank you for confirming - I wanted to ensure I had the facts precisely before addressing your question. I am sorry to report that this is likely to be difficult to resist. The starting point is that the Coop are entitled to do with their land as they wish though of course they will need planning permission for change of use and this is certainly something against which you could object.
The above notwithstanding, you can only take action in respect of coops actions in respect of their land if you can show that they are "substantially interfering" with your rights. The case of B&Q plc v Liverpool & Lancashire Properties Ltd  EWHC 463 (Ch) considered what amounts to substantial interference. It was decided as follows:
The test of an actionable interference is not whether what the grantee is left with is reasonable, but whether insisting on being able to use the whole of what was granted is reasonable.
It is not open to the grantor to deprive the grantee of his preferred means of use and argue that someone else would do things differently, unless the grantee's preference is unreasonable or perverse.
If the grantee has contracted for the relative luxury of an extensive right, he should not be deprived of that right merely because it is a luxury and the reduced right would be all that was reasonably required. The test is not one of necessity or reasonable necessity. Provided that what the grantee is insisting on is not unreasonable in the context of the grant, the question is "can the right of way be substantially and practically exercised as conveniently as before?"
The starting point is therefore to look at the precise wording of the right you have been given in your deeds. If you could point to exclusive use of that strip of land for example this could be a ground for resisting the coops plans. However I assume (though plese correct me if my assumption is incorrect) that your right is limited to a right in common with the owners of the land or words to that effect. If this is the case providing coop do not obstruct your access so that you can no longer reach the rear of your property or that they make it substantially more difficult to do so - e.g. narrow the width so that you can no longer get by without extreme care the sharing the route with other traffic would not amount to grounds for objection providing the access s still safe to use. It would almost certainluy be a condition of their planning permission that any turning complies with all necessary road traffic regulations and so this condition is likely to be satisifed.
If you believe the grant of the right of way goes further than my above assumption, please would you kindly let me have the exact wording and I will be pleased to consider whether you can make a case that it grants you more rights than that set out above. I am sorry otherwise not to give you a more upbeat assessment, but I would not want to give false hope or much less encourage you to spend money seeking an injunction if there is not a reaonable chance of success. If I can assista ny further with the above, please come back to me.
Does the above answer all your questions? If it does, I should be very grateful if you would kindly take a moment to click a rating for my service to you today. Your feedback is important to me. If there is anything else I can help with please reply back to me though