Martin, on the begining u can start with standard 12v battery from screfix, toolstation etc. They maybe not to smallest and light but will do the job. Plus od it, you can bay it now.
The pole u can order from ebay (flag pole), they are similar to sota ones
With time u can upgrade yours equipment for better .
I start with Sealed Lead-Acid Battery 12V 7.0Ah and i still use it. Have also smaler ones
https://www.screwfix.com/p/sealed-lead-acid-battery-12v-7-0ah/38315
Pole i use is simple 8m flag telescopic mast, delivery in few days. Its 114cm long unfolded…
Also thinking aboud upgrade for smaler and lighter but all with time. Will get it some day till then i use whot i have and gives me plesure and fun.
73