Can I make an Enchantment table which can enchant to higher levels then 30?
Sadly, it's impossible to enchant to higher levels than 30 on an enchantment table. In fact, it's only possible to get items enchanted with higher levels in the End Cities.
I think this is not possible in minecraft any more, the only way would be, that you check if the player entchants something and put a higher entchantment level on it and take levels from him. But you would have to check for each item type and each entchandment combination.