If you can get a
Wickes 'Click and collect', invest in a wet vac, they do one for about £40. Ideal for cleaning out drains, and removes the danger of any injury form a sharp object that may be present. Once pot is clear, use a hose to fill it back up, if still blocked, a good plunging with a rod may be enough to clear it. No point shoving rods blindly up from the manhole unless you know exactly where the pipes go.