@JustinMac84 you basically have two options.
First, ask your landlord. There are various grants and schemes for landlords to raise the energy efficiency of their properties.
Secondly, wait. Balcony Solar (aka plug in) is not allowed in the UK. But it looks like that might change soon. https://www.efixx.co.uk/Articles/plug-in-solar-uk-regulations
When / if it does, you'll be able to hang your own panels outside. Probably not as efficient as rooftop, but better than nothing.