There are several problems with using a rotavator, and some of these have been
touched on. Basically they are as follows:

1) The rotavator will probably not 'dig' deep enough to be effective and give
you the desired results.

2) The rotavator will till the soil without giving you the opportunity to break
the soil up as with a fork and remove weed roots as you go, hence the concern
with weeds. Weed seeds are immaterial when it comes to choosing to till the
soil with a rotavator or fork as both systems turn the soil and weed seeds over
and allow some weed seeds to germinate and grow.

3) The rotavator may turn the top soil over, but may compact the soil that the
blades ride over. This can lead to 'panning' which will restrict the ability
of water to drain through the soil, and will also limit the ability of plant
roots to travel down through the soil. Very sandy soils will be least
effected, while clay soils will be worst effected.

If it was up to me II'd spend the money on something else, though whether you
want to or not is up to you. Personally I'd go for a new fork, or something
else that I needed, or maybe a couple of folding seats to sit on whenever I
needed a rest, or maybe a new flask for my tea/coffee, or some fancy biscuits
to have when I took a rest.

The list could go ever on, but I won't indulge myself. It does however prompt
me to think of some things to ask for for Christmas. I now have some ideas of
things to ask for when relatives ask me what I want.

All the best with the new plot.

Dave.