Sash window repair - epoxy resin?

[bureaucrazy]

I need to restore a neglected sash window. There is not much actual wet rot, just a bit in the corner that I will fix with a small splice. However, the cill is in a bad state. It's not rotten but has many small horizontal splits in the surface from water expanding inside over time. The top layer of wood have seperated in little "bars" where the splitting has occured making the surface a bit uneven. The split wood has been painted over in the past, due to the unevenness, the old paint will be difficult to remove with heat or sanding. I don't want to use nitromors as it will run inside the splits and may react with any filling products, etc. I have heard that proffessional restoration companies use advanced cartridge gun epoxy resin products to bond inside the splits and laminate the damaged surface with a strong, slightly flexible waterproof resin, which can be sanded and painted just like wood once set. They don't sell this in DIY stores and I have no idea where to get it from or what is the most suitable product. I expect to pay around £30. I looked in a marine chandlery but they only had small tubes for filling holes and adhesives. Please reccommend a product. Thanks

update: anyone tried timbabuild ehb?

 

[ModernMaterials]

If this is going to have a solid coloured, painted finish, then you will need to use microporous paint.
This doesnt coat solidly like interior paint but allows moisture trapped in timber to evaporate through its small holes or 'micropores'. ( It still looks like normal paint).
It aint cheap.
But restoring original sashes is worth spending money on.
I have used it myself , I used the Leyland variety but Dulux also make one called weathershield.
I just used the cheapest filler i could find which i already had.
You have to cut out any weak or rotten timber first then do a nice job with the filler.