Welcome. But I'm not sure my reply will be entirely welcomed, which of necessity will be blunt.
Necessity, your safety!
Four weeks Surfing you think you may be edging into being intermediate!
Just what can you do in riding a wave?
An Indonesian back pack surf trip for a month ( Great but we will get to the basics of that after your surfing needs)
Batu Karas, Java some surf schools , mainly right handlers over coral and lava reefs, Karang is one such,, next gentle learners break not so bad right handed and good for learning.
Legok Pari a certain amount of sand! Next your first left hander Bulak Bendak, a experienced level left hander.
Be prepared to buy limes or iodine wipes to sterilise the coral cuts.
Next what sort of board will you be riding and back packing with? That will interesting, google map check the road conditions, some main roads, little more than one car wide, ithrough the jungle well away from the beaches, little side roads, do. you know which one lead to beachs, the central south of Java it is very hard to access beaches beyond East Java you need to island hop, ferries Java to Bali Java to Lombok or Java, Bali Lombok, ferry Terminals in Lombok at NW coast of Lombok surf in south!
There are buses somewhere, sometimes, if you backpack please expect to pay for any rides, you will be considered rich, think cheap and you will be considered rude and arrogant. Karma is alive and well in Indonesia
Have you been to an emerging country with huge areas of jungle and real poverty, but cultural richness.
Java Muslim. Bali Hindu, and Muslim, Lombok, Muslim and Hindu, .
People are very welcoming when respected! Modesty and respectful behaviour at all times!
How old are you?
Are you self sufficient in surf safety and self rescue as most locations have nothing to offer if you can look after yourself, you will be on your own!
It is a big adventure ,but nowhere near as connected as traveling in Australia, USA or Europe,.
Outside cities the further off track you go the less English or any other language is spoken
Bahasa Indonesian is even rare in some areas!
Do you have travel vaccinnations/ medications, malaria, typhoid encephalitis , severe bacterial infections and dysentery just covering a few.
My honest suggestions for you areto head from one clear surf destination to another, go to surf camps learn there!
Surf condition can change brutally from tide to tide, a benign spot can shift in minutes as a pulse of deep Indian Ocean swell arrives.
Buy a book I recommend to all new Indonesian travellers should have, Indo Surf and Lingo by Peter Neely, basic language, a run down of heaps of surf Spots.
Stay your whole stay at Batu Karas, as so much of your surf time will be spent in fruitless ( only in not getting much surf) travel.
Just a question where was your 4 weeks surf experience gained?
I am not being disrespectful of you , but there is so much risk for the novice.
Ask more questions we can tell you more

BTW have been surfing through the length of Indonesia since 1979, short and long boards.
There others who are resident there!
I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun! 冲浪爷爷