If you want it to be safe, not very difficult.
The unearthed lighting is common in houses of that age. You just have to use all-plastic switches and fittings. No metal.
The sockets, you might mean there are unfused spurs with multiple sockets on each. You could have them modified to be fused spurs. This will be fine for low loads such as table lamps, PCs, TVs, phone chargers, but you can't have more than one significant load on each (washer, drier, toaster, kettle, fan heater). This is probably not much hardship. The sockets on the original ring will work as normal. It would be best to add an RCD on, at least, the socket circuits, there might be one or two, and anything serving the bathroom. A house of this age probably has a Wylex Standard CU which is not really suitable for modernisation.
The kitchen and the utility room (where there are lots of appliances) would probably most benefit from new electrical circuit(s). This would be the time to add lots of sockets above the worktop, and two cooker circuits (one on each side in case you move the plan around) and a separate freezer circuit; and new lighting, and an extractor hood point.
the other rooms can wait if necessary; though, if you can afford it, the best time to have rewiring done is just after you buy, and before you start redecorating, reflooring, refitting the kitchen.
Rewiring is to be expected in a house of this age so the sale price might already reflect it.
You will want to add RCDs, though my recommendation is RCBOs which will cost more but are much better.
If you do a partial rewire, ask for a 20-way consumer unit, which will have space for future additional circuits, and leave all the old circuits on the old CU until they are replaced. The cost of the larger empty box is insignificant.