Yups that would be the best option.  Call Dell out of warranty UK repairs and get a Quote for the battery  0844 444 3141 Best of luck though the model is 3 years old and Dell may not have batteries in stock.   
My Dell XPS 15 7590 needs a replacement battery, I looked around and it's a Dell 6-cell 97 Wh Lithium-Ion? Though I'm unsure if it's that's the specific model that will work on my laptop (I can't verify compatibility) nor I am unable to obtain it, I don't know what to do, I kinda need an urgent battery replacement since my laptop is progressively unable to hold charge and I'm out of warranty ??
Dell XPS 15 7590 Battery replacement