Before you go purchasing anything I would try using a Notch Filter to remove the hum - it’s likely to be mains hum at 50Hz in the UK or 60Hz in the US YMMV. If that sounds ok to you then save your money. 
See this page in the Manual: Audacity Manual
If you have clicks on your LPs you may want to consider buying Brain Davies’ Click Repair software as it produces excellent results - see this sticky thread: Click/pop removal - ClickRepair software
You may find this workflow tutorial from the Manual helpful: Audacity Manual
It’s part of this full set of tutorials: Audacity Manual
WC