so i will have to invest in a spare computer and insure it has internet access...
No. You can rent out a VPS for <$10 per quarter.
however what happens if i am travelling and i need to switch the gunbot off?
Nothing really, you can turn it on again whenever you want. However, for optimal results you need it to run 24/7.
Is there any other option where can i leave the bot running all day long apart from buying another computer...
As said, rent a VPS.