Webapp and service worker developed for a simple Php website.

I am looking for a developer to create me a webapp starting framework which enables me to enter an accident record using a mobile device. When an accident occurs the end user goes through the following process.

1) finds the person it relates to, search by name and pulls back from a central table.
2) Records information of the accident, where occurred, what happened, detail of injury, treatment done, next steps, these are all pre-populated picking lists to have uniform data for reporting.
3) Save the record to the system.

Ideally when a network connection is not available they should be able to perform an offline entry where they can enter the persons name, class name, registration group and store this into a local cache.
Then when a network connection is re-established they should be able to upload the data to a temporary table where it can be matched in the back office manually.

The main system is developed in Bootstrap 4, PHP and MYSQL.
I have the schema in place for the persons information, accident criteria etc and can provide access to this.

The offline table for matching is yet to be created.

The webapp should be one which can be easily updated should more information be required to be added in the future.

If you need further information please do not hesitate to contact me.

I would also be interested in the approximate timescales to produce.