Need a bit of clarification - first, how long has the plant been in its current position (if its longer than 3 years, very difficult) and second, do you mean a Robinia pseudacacia or do you mean Photinia Red Robin? Not that it matters if whatever it is has been too long in its current position...

It is about 4 years old but it was growing not very well in a pot when it was given to me. I put it in the garden last august I thought it would die so I wasn't to fussy where I planted it but it as out grown the space I put it in. It just gets bigger and bigger it needs a more open space because at the moment it is pushed up against a fence

Worth a try at moving it then, if you only put it in the ground last year. Work out where you can accommodate it, then dig the area over a bit. Wait for the weather to become more autumnal, cooler and damper, say into October, then dig it up, trying to keep a good rootball and not break any roots extending from it, and transfer to the new place. Make sure the hole you dig in the new spot is the right depth, shape and size so that you don't have to cramp or bend roots to fit into it. Water in well and keep watered if the weather is dry, up to November.