A UHD or 4k TV may not produce as good a picture as a FHD TV especially at the same price. The FHD set may have better color and black levels. It may also have less artifacts than the UHD set since it will have to process all non 4k video up to 4k. Cheaper sets tend to skimp out on this since it is expensive to do. HDR is actually a bigger improvement to the picture quality than 4k but that will be more expensive.
I would go for the biggest FHD set you can afford if 4k sources are not available to you soon..