First bike / MX advice?

[MG]

Hi guys, just after some advice.

Did the Yamaha Off Road Experience at Golding Barn last weekend, it was my first go on an off road bike and I absolutely loved it. Having done quite a bit of mountain biking before, and knowing how to ride a motorbike really helped, and I felt like I picked up a lot over the course of the day.

Now to my question - I'm on placement from uni for the year, so I have some time and most importantly money to get an off road bike. I was looking at doing some trackdays on my CB but my restricted licence causes problems there, so I thought I'd look at going off road. I have flackwell heath and slough mx tracks not far from my house, so am I right in thinking that as a noob I can just get a bike and go there on a practice day and ride?

As to the bike, I'm looking at either a 125 2T or a 250F. I rode a YZ250F at the experience day, which felt very quick, but looking on ebay I see them coming in between £1600 & £3k. Ideally I'm looking to spend <£1500, so I've also been looking at a YZ125 or CR125. Obviously I'm not going to be racing the bike, and I have access to a workshop to maintain it, so which is the more suitable bike for a beginner? Any other suggestions would be great!

Thanks
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'03 Honda Cityfly 125 > '02 Honda CB500S > '98 Honda CBR600F