Hello Caelacoo and welcome to the forum! Beautiful pup!
There is a new and helpful addition to the allaboutdogfood website which might help with (UK) stores which provide dog food and with buying dog food online.
David descibes this as:
"Finding your favourite dog foods locally has never been easier! Simply head over to the store finder, enter your location and the brand you're looking for and hey presto! You can even filter the results to show only businesses with specific doggy services like training, walking, vet care and home delivery!"
Here are the links to the relevant information:
Buy dog food locally
and Buy dog food online