Cheers for the ideas Vogue re: my current plan/upgrade options.
I already have 250Gb, unmetered with 500Mb RAM, that cost 147.63€ for 12 months so I can...
1. Get a second one, (+ 250Gb of space) and pay 147.63€ again.
2. Add 5x 50Gb of space to my existing box for (19.99€ per 50Gb x5) = 99.95€.
3. Upgrade my plan entirely to a 500Gb one at 24.95€ / month (€299.40

) minus the 147.63€ I already paid = 151.77€
- That is quite a price difference! The cheapest being the 'add to my existing box' option #2. I'm erring towards that. Maybe just adding 100Gb to it at first and seeing how I get on. I just hope I don't start falling foul of RAM/hardware limitations. Putting all your eggs in one basket and all that.
