Dead(ish) battery + no electricity in garage - suggestions?

thanks hmagic l have jumpstarter https://www.amazon.co.uk/DBPOWER-8000mAh-Portable-Starter-Battery/dp/B013UBRZUS/ref=pd_sbs_263_9?_encoding=UTF8&psc=1&refRID=11DJ6XA2GCXGB8WYA1XW

last time l tried battery was so dead it wouldn’t work. 

RAC came with big guns and wake it up for me