I'm gonna give you some general tips on how I practiced when i first came upon this problem. Just remember that something like hand coordination takes practice and doesn't come overnight, and the more you play, the more comfortable it will seem when you join your hands to play HT.
1) Practice scales, in many variations.
What i like to do is after i can play a scale at a pretty decent speed, I like to implement some exercises on that scale. I suggest you particularly play the scales with the same key as the pieces you are currently practicing.
So, after you can play a scale relatively well, I would start by doing several exercises. First, try to play the RH Legato and the LH staccato, and vice versa. This will improve hand independence so that you can play with different articulation in each hand. Though this seems to be the opposite of what you want, practicing hand independence will make it easier for you to join hands.
Also, try to play the hands with different speeds. This worked wonders for me. Sometimes in repertoire you will come across passages with different note values for each hand. For this i used to play the scale with quarter notes in the RH and half notes in the LH, and vice versa. This helped me a lot.
2) I would suggest playing some Bach. His music teaches hand independence quite well, and as i said before, when your hands are more independent, it will seem easier when you put them together, and after a while you can start combining the melodies with each other until you find the sound you're trying to achieve.
3) Practice HS (hands separately) until you can play it above the required tempo, and when you start playing HT, play way slower, so you can ease into the piece with both hands. If the passages you are playing requires to be play fast, try to play in SLOW MOTION INSTEAD OF SLOWING DOWN. This is to keep the hand and body motions you practiced HS at a high speed, which will be lost when played at a slow tempo, and will create speed walls when you try to get back up to speed. So basically, play with the same motion/movements BUT IN SLOW MOTION, and once you get comfortable with the slow motion movements, gradually speed up until you get your HS speed back.
4) Search the forum for posts by Bernhard about hand co-ordination and the "Dropping notes" practice technique. This involved playing one hands and randomly adding notes of the other hand at a comfortable pace (pace for yourself, I mean).
I'm not an advanced pianist myself, but these tips have helped me a lot in getting many technical challenges down. I'm sure others (more experienced) will help you later on, but i'm quite convinced that this advice will keep you going until then. It could help you if you put some time and effort into it. Good luck
